The first thing to point out is that SharePoint is built on top of ASP.Net, so on the plus side you get to leverage some of your skills and on the negative side, if you're bored with .Net then this will be basically more of the same.
Whether or not it will be beneficial to you depends on a lot of circumstances but SharePoint is Microsoft's biggest growing product and made them over a billion dollars in the last financial year. I remember reading that for every dollar spent on SharePoint licenses, seven dollars was spent on consulting and services outside Microsoft so that's a large and vibrant ecosystem with a lot of opportunity.